Outbreak of Serratia marcescens Bloodstream and Central Nervous System Infections After Interventional Pain Management Procedures

To determine the cause of an outbreak of Serratia marcescens infections in patients after interventional pain management procedures at an outpatient pain clinic.We conducted a case-control study and collected clinical and environmental samples.We identified 5 culture-confirmed case-patients and 2 presumptive case-patients who had no bacteria recovered from cultures. The 7 case-patients were compared with 28 controls who underwent procedures at the same clinic but did not develop symptoms of infection. All confirmed case-patients had S. marcescens bloodstream infections; 2 had concurrent S. marcescens central nervous system infections. Case-patients were more likely than controls to have procedures that used contrast solution or entered the epidural or intervertebral disc space (Por =0.01 for each). All S. marcescens clinical isolates were indistinguishable by pulsed-field gel electrophoresis. We did not isolate S. marcescens from medications or environmental samples; however, S. marcescens was shown to survive and grow in contrast solution that was experimentally contaminated for up to 30 days. Single-dose vials of medication, including contrast solution, were used for multiple procedures; multiple medications were accessed with a common needle and syringe.The findings of this investigation suggest contamination of a common medication, likely contrast solution, as the source of the outbreak. Practices, such as reusing single-dose medication vials and using a common needle and syringe to access multiple medications, could have led to contamination and propagation of S. marcescens and should be avoided in interventional pain management procedures.